Driving control apparatus, image pickup apparatus, and control method

ABSTRACT

A driving control apparatus is configured to control a driving unit that moves relative to each other a vibrator that is excited to vibrate by applying a first driving signal and a second driving signal that have a phase difference with each other, and a contact member that contacts the vibrator. The driving control apparatus includes a first control unit configured to control the phase difference, and a second control unit configured to control a voltage amplitude of each of the first driving signal and the second driving signal. The second control unit controls the voltage amplitude so that a change rate of the voltage amplitude increases as an absolute value of the phase difference decreases.

BACKGROUND Technical Field

One of the aspects of the disclosure relates to a driving controlapparatus, an image pickup apparatus, and a control method.

Description of the Related Art

Japanese Patent Laid-Open No. 2021-92717 discloses a configuration thatreduces a voltage amplitude of a driving signal during low-velocitydriving of a vibration wave motor, and thereby can suppress unnecessaryvibration during the low-velocity driving and reduce driving noise thatwould occur during the low-velocity driving.

However, reducing the voltage amplitude of the driving signal of thevibration wave motor causes the configuration to be more susceptible tothe friction of the driving unit and the driving load, and causes thevibration wave motor to reduce control performance.

SUMMARY

One of the aspects of the disclosure provides a driving controlapparatus that can suppress noise and maintain control performanceduring low-velocity driving of a vibration wave motor.

A driving control apparatus according to one aspect of the disclosure isconfigured to control a driving unit that moves relative to each other avibrator that is excited to vibrate by applying a first driving signaland a second driving signal that have a phase difference with eachother, and a contact member that contacts the vibrator. The drivingcontrol apparatus includes at least one processor, and a memory coupledto the at least one processor, the memory having instructions that, in acase where executed by the processor, perform operations as a firstcontrol unit configured to control the phase difference, and a secondcontrol unit configured to control a voltage amplitude of each of thefirst driving signal and the second driving signal. The second controlunit controls the voltage amplitude so that a change rate of the voltageamplitude increases as an absolute value of the phase difference or atarget velocity of the driving unit decreases.

An image pickup apparatus including the above driving control apparatusand a control method corresponding to the above driving controlapparatus also constitute another aspect of the disclosure.

Further features of the disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an image pickup apparatus according toan embodiment of the disclosure.

FIG. 2 is a block diagram of the image pickup apparatus.

FIG. 3 is a block diagram of a pan rotation unit and a barrel rotationdriving unit.

FIG. 4 is a sectional view of a vibrator.

FIG. 5 illustrates a relationship between a driving frequency of thevibrator and a driving velocity of the rotating unit.

FIG. 6 is a flowchart for explaining one example of an operation of theimage pickup apparatus.

FIG. 7 explains a method of calculating an absolute angle of the cameraand an image stabilizing amount.

FIGS. 8A and 8B explain a direction of the image pickup apparatus.

FIGS. 9A to 9D explain area division.

FIGS. 10A to 10C explain area division in a captured image.

FIGS. 11A and 11B explain area division in a captured image.

FIG. 12 explains person detection for each area in a captured image.

FIG. 13 explains object detection for each area within a captured image.

FIG. 14 explains scene detection for each area in a captured image.

FIG. 15 is a flowchart for explaining sound detection.

FIGS. 16A to 16C explain motion detection in a captured image.

FIG. 17 explains management of the number of captured images for eacharea.

FIG. 18 explains management of the number of captured images for eachregistered object that has received personal authentication.

FIG. 19 explains management of the number of captured images for eachregistered object that has been recognized as an object (non-person).

FIG. 20 explains management of the number of captured images for eachscene.

FIG. 21 is a flowchart for explaining calculation based on unsearchedtime.

FIGS. 22A and 22B explain search target angle calculation for eachscene.

FIG. 23 illustrates an example of a relationship between a phasedifference between voltages applied to the vibrator and a voltageamplitude.

FIGS. 24A to 24C illustrate a relationship between the phase differencebetween the voltages applied to the vibrator and a driving velocitydepending on a difference in voltage amplitude.

FIG. 25 is a flowchart for explaining a method of determining thevoltage amplitude according to the phase difference.

FIG. 26 is a block diagram of a pan rotation unit and a barrel rotationdriving unit.

FIG. 27 illustrates an example of measurement data of the phasedifference and the driving velocity.

FIG. 28 is a flowchart for measuring and storing a phasedifference-velocity characteristic.

FIG. 29 is a block diagram of a pan rotation unit and a barrel rotationdriving unit.

FIG. 30 illustrates an example of measurement data of the voltageamplitude and the driving velocity.

FIG. 31 is a flowchart for measuring and storing a voltageamplitude-velocity characteristic.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a detailed description willbe given of embodiments according to the disclosure. Correspondingelements in respective figures will be designated by the same referencenumerals, and a duplicate description thereof will be omitted.

Configuration of Image Pickup Apparatus

FIG. 1 schematically illustrates an image pickup apparatus (camerahereinafter) 101 according to one embodiment of the disclosure. Thecamera 101 includes an operation member such as a power switch foroperating the camera. A barrel 102 includes an imaging lens unit and animage sensor for imaging, and is attached to the camera 101 androtatable relative to a fixing unit 103. A tilt rotation unit 104includes a motor driving mechanism that rotates the barrel 102 in apitch direction. A pan rotation unit 105 includes a motor drivingmechanism that rotates the barrel 102 in a yawing direction. A drivingunit includes the tilt rotation unit 104 and the pan rotation unit 105.An angular velocity sensor 106 (gyro sensor) for detecting angularvelocities in three axial directions and an acceleration sensor 107 fordetecting accelerations in three axial directions are mounted on thefixing unit 103.

FIG. 2 is a block diagram of the camera 101. A zoom unit 201 includes azoom lens that performs magnification variation. A zoom driving controlunit 202 controls driving of the zoom unit 201. A focus unit 203includes a lens for focusing. A focus driving control unit 204 controlsdriving of the focus unit 203. In an imaging unit 205, the image sensorreceives incident light through each lens unit, and outputs chargeinformation corresponding to the light amount as analog image data to animage processing unit 206.

The image processing unit 206 applies image processing such asdistortion correction, white balance adjustment, and color interpolationprocessing to digital image data output by A/D conversion, and outputsapplied digital image data. The digital image data output from the imageprocessing unit 206 is converted into a recording format such as a JPEGformat, and recorded in a recording medium such as a nonvolatile memoryby the image recording unit 207.

A barrel rotation driving unit (driving control apparatus) 112 drivesthe tilt rotation unit 104 and pan rotation unit 105 to drive the barrel102 in the tilt and panning directions. The barrel rotation driving unitincludes at least one processor, and a memory coupled to the at leastone processor, the memory having instructions that, when executed by theprocessor, perform operations as a first control unit and a secondcontrol unit, which will be described below. An apparatus shakedetecting unit 208 calculates a rotation angle, a shift amount, etc. ofthe camera 101 based on signals from the angular velocity sensor 106 andthe acceleration sensor 107. An apparatus movement detecting unit 209detects movement of the camera 101 using positional information from aGlobal Positioning System (GPS) and movement detecting unit such as anacceleration sensor. GPS may be provided to the camera 101 or anexternal GPS detecting unit. The movement of the camera 101 can also bedetected by the apparatus shake detecting unit 208, but it is difficultfor the apparatus shake detecting unit 208 to detect a wide moving rangeof the camera 101 due to the characteristic of the acceleration sensor.Accordingly, a narrow moving range of the camera 101 is detected by theapparatus shake detecting unit 208, and the wide moving range of thecamera 101 is detected by the apparatus movement detecting unit 209. Asound input unit 210 acquires a sound signal from a microphone providedto the camera 101. An operation unit 211 includes the power button andbuttons for changing settings of the camera 101. A control unit 212controls the entire camera 101.

FIG. 3 is a block diagram of the pan rotation unit 105 and the barrelrotation driving unit 112. Since the tilt rotation unit 104 has aconfiguration similar to that of the pan rotation unit 105 except for adriving shaft, only the pan rotation unit 105 will be described in thisembodiment. A rotating unit (contact member) 1051 rotates the barrel 102in the panning direction. A vibrator 1052 is an actuator in whichvibration is excited by applying a first driving signal and a seconddriving signal having a phase difference, and is used to rotate therotating unit 1051 in the panning direction. The pan rotation unit 105moves the vibrator 1052 and the rotating unit 1051 that contacts thevibrator 1052 relative to each other.

FIG. 4 is a sectional view of the vibrator 1052. In FIG. 4 , an x-axisis a moving direction (feeding direction) of the rotating unit 1051, anda y-axis is a direction orthogonal to the moving direction (upthrustdirection). The vibrator 1052 includes electrodes 401 a and 401 b,piezoelectric elements 402 a and 402 b, and a stator 403. In driving therotating unit 1051, two-phase voltages with a different phase suppliedfrom a driving circuit 1054 are applied to the electrodes 401 a and 401b. In a case where the two-phase voltages are applied to the electrodes401 a and 401 b, the piezoelectric elements 402 a and 402 b expand andcontract due to the inverse piezoelectric effect, and two types ofstanding waves are generated in the stator 403. An approximatelyelliptical motion is generated at the contact portion between the stator403 and the rotating unit 1051 by combining the two types of standingwaves. In a case where two-phase sinusoidal voltages having apredetermined phase difference are applied to the electrodes 401 a and401 b, an elliptical vibration having a locus 404 is generated at apoint P of the stator 403. In a case where two-phase voltages having aphase difference larger than that of the two-phase voltages at which theelliptical vibration of the locus 404 is generated are applied to theelectrodes 401 a and 401 b, elliptical vibration having a locus 405 isgenerated at the point P. The elliptical vibration having the locus 405has a larger component in the feeding direction than that of theelliptical vibration of locus 404. Thus changing the phase differencebetween the two-phase voltages can change a ratio of the component inthe feeding direction and the component in the upthrust direction, andadjust the driving velocity of the rotating unit 1051. In a case wheretwo-phase voltages having a frequency (driving frequency) lower thanthat of the two-phase voltages that cause the elliptical vibrationhaving the locus 405 are applied to the electrodes 401 a and 401 b(approaching the resonance frequency of the vibrator 1052), anelliptical vibration having a locus 406 is generated at the point P. Theelliptical vibration having the locus 406 has larger components in thefeeding direction and upthrust direction than those of the ellipticalvibration having the locus 405. Thus changing the frequency of thetwo-phase voltages can also change the driving velocity of the rotatingunit 1051. Alternatively, the magnitude of the elliptical vibration maybe changed by changing the (voltage) amplitude of the two-phasevoltages.

An ultrasonic motor as the vibration wave motor according to thisembodiment is controlled using a driving frequency in an ultrasonicrange higher than the resonance frequency. A velocity controlling methodincludes a method of fixing a phase difference and of changing thedriving frequency (frequency control mode), a method of fixing thedriving frequency and changing the phase difference (phase differencecontrol mode), and a method of changing both the driving frequency andthe phase difference. The phase difference control mode has a low outputbut enables highly accurate positioning, and is suitable for a case thatrequires high accuracy of a stop position, and a case that usesmicro-driving. On the other hand, the frequency control mode is suitablefor a case that requires the rotating unit 1051 to be moved at highvelocity due to its high output, or a case where the load on thevibrator 1052 increases due to a low-temperature environment ordeterioration of the durability of the rotating unit 1051.

A temperature sensor 1053 measures the temperature of the vibrator 1052.The temperature detection result is used to thermally correct thefrequency of the voltages applied to the vibrator 1052. A positionsensor 1056 detects a rotation position of the rotating unit 1051 bydetecting, as an electric signal through a light receiving unit,reflected light of a light emission signal emitted from a light emittingunit to a pattern engraved on an optical scale attached to the rotatingunit 1051. The driving circuit 1054 performs amplification and signalconversion such that the voltage generated by a driving signalgenerating circuit 1128 (which will be described below) can become avoltage that can drive the vibrator 1052.

An analog-to-digital converter (hereinafter referred to as an ADC) 1121analog-to-digital converts the electrical signal detected by theposition sensor 1056. A position calculating unit 1122 finds a rotationposition of the rotating unit 1051 based on sensor information digitizedby the ADC 1121. A target position setting unit 1123 sets a targetrotation position in the panning direction based on a rotationinstruction from the operation unit 211. AProportional-Integral-Differential (PID) calculating unit 1124 performsPID control calculation based on a deviation between the target rotationposition of the rotating unit 1051 set by the target position settingunit 1123 and the rotation position of the rotating unit 1051 obtainedby the position calculating unit 1122. A conversion unit (first controlunit, second control unit) 1127 converts a control amount calculated bythe PID calculating unit 1124 into a phase difference and a frequency ofthe two-phase voltages. A limiting unit 1125 limits change amounts inthe phase difference, voltage amplitude, and frequency of the two-phasevoltages. The driving signal generating circuit 1128 generates a drivingsignal according to the phase difference, voltage amplitude, andfrequency of the two-phase voltages determined by the conversion unit1127. The driving signal is a rectangular wave signal. The voltageamplitude of the voltages applied to the vibrator 1052 changes accordingto the ratio (duty ratio) of the pulse width of the rectangular wave inone cycle of the driving signal. As the duty ratio increases, thevoltage amplitude increases, and as the duty ratio decreases, thevoltage amplitude decreases. The voltage amplitude may be changed by amethod other than the pulse width modulation (PWM) method.

Relationship Between Driving Frequency of Vibrator 1052 and DrivingVelocity of Rotating Unit 1051

FIG. 5 illustrates a relationship (frequency-velocity (FV)characteristic) between the driving frequency of the vibrator 1052 andthe driving velocity of the rotating unit 1051, illustrating temperaturechange in the FV characteristic and a prohibited frequency range.Reference numeral 501 denotes an FV curve at reference temperature tsd.Reference numeral 502 denotes an FV curve in a case where thetemperature changes by Δα from the reference temperature tsd. A phasedifference between the two-phase driving voltages in the FV curves 501and 502 is 90°. Vsd denotes a reference velocity in a case where thevibrator 1052 is corrected thermally (based on the temperature).

A driving frequency Fp during phase difference control varies dependingon the temperature and is expressed by the following expression (1).Fp=Fini−k·(tx−tsd)  (1)where tx is temperature detected by the temperature sensor 1053, Fini isa starting frequency at which the driving velocity becomes the referencevelocity Vsd in a case where the two-phase voltages with a phasedifference of 90° are applied to the vibrator 1052 at the referencetemperature tsd, and k is a temperature correction coefficient for thestarting frequency Fini.

Fα is a driving frequency in a case where the temperature changes fromthe reference temperature tsd by Δα. Fβ is a driving frequency in a casewhere the temperature changes from the reference temperature tsd by Δβ.

Reference numeral 504 denotes a prohibited frequency range of thefrequency of the voltages applied to the vibrator 1052. The prohibitedfrequency range 504 is a frequency range that may adversely affect animage and operation of the camera 101 due to mechanical vibration causedby the vibrator 1052 and electrical noise generated by the drivingcircuit 1054.

In a case where the temperature changes from the reference temperaturetsd by Δα, the driving frequency Fα falls within the prohibitedfrequency range 504. In that case, the driving frequency is set to thedriving frequency Fβ that is outside the prohibited frequency range 504and closest to the driving frequency Fα. If the driving frequency is setto the driving frequency Fβ in a case where the temperature changes fromthe reference temperature tsd by Δβ, a velocity Vab in a case where thephase difference between the two-phase voltages is 90° is higher thanthe reference velocity Vsd. In a case where position control of therotating unit 1051 is made in this state, a change amount in therotating unit 1051 becomes larger than expected, and proper control isunavailable. In the worst case, it becomes an uncontrollable(oscillation) state.

In a case where the thermally corrected driving frequency in the FVcurve 502 falls within the prohibited frequency range 504, the voltageamplitude of the two-phase voltages is adjusted so that the drivingvelocity in a case where the phase difference is 90° becomes thereference velocity Vsd.

In a case where a voltage amplitude in a case where the vibrator 1052 isat the reference temperature tsd is Asd, a voltage amplitude Aβ on theFV curve 503 is expressed by the following expression (2).Aβ=(Vsd/Vab)·Asd  (2)

In a case where the driving frequency thus falls within the prohibitedfrequency range 504 due to the temperature correction, it is necessaryto simultaneously change the driving frequency and the voltage amplitudein order to accord the control performance of the rotating unit 1051with the pre-correction performance. Since the driving frequency andvoltage amplitude are changed simultaneously and discontinuously,unnecessary vibrations are generated in the vibrator 1052 due to changesin the FV characteristic, and uneven rotation or noise may occur in therotating unit 1051. In a case where uneven rotation occurs during imagerecording, image blur may be captured in the rotating direction due tothe influence of the uneven rotation. The above problem does not occurif no thermal correction of the driving frequency is made, but thechange amount of the rotating unit 1051 becomes improper if the positioncontrol of the rotating unit 1051 is made. As a result, uneven rotationmay occur because load fluctuations caused by the rotation positionchanges of the rotating unit 1051 cannot be suppressed, and a blurredimage may be captured. A method for solving this problem will bedescribed below.

Operation of Image Pickup Apparatus

FIG. 6 is a flowchart for explaining an example of the operation of thecamera 101. The camera 101 has an automatic object searching function,which is started in a case where the camera 101 is powered on, andexecutes automatic object searching and automatic imaging.

In a case where the power button is operated in the operation unit 211,the control unit 212 performs various initial settings(imaging/automatic searching, etc.) in step S601. The initialization ofthe automatic searching performs processing such as initialization of animportance (or priority) level (or rating or point or score), which willbe described below. In a case where the initial setting ends and imageinformation from the image sensor can be acquired, the image processingunit 206 generates an image for object detection using a signal acquiredfrom the imaging unit 205. An object such as a person or an object isdetected using the generated image. In detecting the person, his faceand body are detected. In the face detection processing, a pattern fordetermining the face of the person is previously determined, and aportion included in an image that matches the pattern can be detected asa face image of the person. Face credibility indicating the probabilitythat the object is a face is also simultaneously calculated. The facecredibility is calculated, for example, from the size of the face areain the image, the matching degree with the face pattern, and the like.As for object recognition, similarly, an object matching apre-registered pattern can be recognized. There is also a method ofextracting an object using a histogram of hue, chroma, etc. in an image.This method divides a distribution derived from the histogram of thehue, chroma, etc. into a plurality of sections regarding an object imagecaptured within an imaging angle of view, and classifies the capturedimage for each section. For example, a histogram of a plurality of colorcomponents is created for the captured image and is divided according tothe mountain-shaped distribution range, and the captured image isclassified by an area belonging to a combination of the same section,and the image area of the object is recognized. By calculating anevaluation value for each image area of the recognized object, the imagearea of the object with the highest evaluation value can be determinedas the main object area.

In step S602, the control unit 212 starts moving image capturing. Instep S603, the control unit 212 acquires imaging information such asobject detection information. In step S604, the control unit 212acquires angular velocity information from the apparatus shake detectingunit 208. In step S605, the control unit 212 acquires accelerationinformation from the apparatus shake detecting unit 208. In step S606,the control unit 212 calculates an absolute angle of the camera from theangular velocity information and the acceleration information. In stepS607, the control unit 212 calculates an image stabilizing amount forsuppressing image blur that occurs in a case where the camera 101 ishand-held or wearable on the human body.

Since the angular velocity sensor 106 and the acceleration sensor 107are mounted on the fixing unit 103, the angular velocity information andthe acceleration information are information at the position of thefixing unit 103, and the absolute angle of the camera calculated basedon the information is an absolute angle at the position of the fixingunit 103. In correcting rotational blur of the barrel 102 (blur of theimage sensor), an image stabilizing amount is calculated using acorrection angle based on the angular velocity information at theposition of the fixing unit 103. The control unit 212 performs imagestabilization by driving the tilt rotation unit 104 and the pan rotationunit 105 via the barrel rotation driving unit 112 based on the imagestabilizing amount and by rotating the barrel 102.

Calculating Method of Absolute Angle of Camera and Image StabilizingAmount

FIG. 7 explains a calculating method of the absolute angle of the cameraand the image stabilizing amount. A description will now be given of amethod for calculating the absolute angle of the camera. An absolutepitch angle calculating unit 701, an absolute yaw angle calculating unit702, and an absolute roll angle calculating unit 703 calculate absoluteangles in the pitch, yaw, and roll directions, respectively, using anoutput of the angular velocity sensor 106 and an output of theacceleration sensor 107. Thereby, the absolute angle of the camera atthe positions of the angular velocity sensor 106 and the accelerationsensor 107, that is, the absolute angle of the camera at the position ofthe fixing unit 103 is calculated.

First, the absolute angles of the camera in the roll direction, pitchdirection, and yawing direction (acceleration-calculated absolute rollangle, acceleration-calculated absolute pitch angle, andacceleration-calculated absolute yaw angle) are calculated based on arelationship between the outputs of the axes of the acceleration sensor107. However, the tilt angle can be accurately calculated in a casewhere the camera 101 is stationary and is not affected by externalacceleration, that is, in a case where gravitational acceleration isdominant in the acceleration detected by the acceleration sensor 107.The influence of acceleration (vibration acceleration) other than thegravitational acceleration increases during imaging while the camera 101is moved, for example, while the photographer is holding the camera andwalking, while the camera 101 is fixed and attached to part of the body,and while the camera 101 is attached to a vehicle such as a car or amotorcycle and captures an image. Therefore, it is difficult tocalculate an accurate absolute angle of the camera. Even in a case wherethe absolute angle of the camera is estimated with the angular velocitysensor 106, the orientation angle can be estimated by integrating theoutput of the angular velocity sensor 106 but it is difficult toaccurately calculate the absolute angle because an error caused by theintegration is included.

Accordingly, a peculiar noise range of each of the angular velocitysensor 106 and the acceleration sensor 107 is removed, and the signalsare combined by sensor fusion to calculate the absolute angle. Morespecifically, the absolute angles are calculated with a Kalman filter, acomplementary filter, etc., and low-frequency noise that most affectsthe integration error of the angular velocity sensor 106 andhigh-frequency noise that most affects the calculation error caused bydisturbance of the acceleration sensor 107 are eliminated, and thesignals are combined. The sensor fusion enables an accurate absoluteangle to be calculated while noise is removed.

Thus, the absolute pitch angle is calculated by the sensor fusion of thegyro-pitch angular velocity from the angular velocity sensor 106 and theacceleration-calculated absolute pitch angle. The absolute yaw angle iscalculated by the sensor fusion of the gyro-yaw angular velocity fromthe angular velocity sensor 106 and the acceleration-calculated absoluteyaw angle. The absolute roll angle is calculated by the sensor fusion ofthe gyro-roll angular velocity from the angular velocity sensor 106 andthe acceleration-calculated absolute roll angle.

The absolute angle is calculated by the angular velocity sensor 106 inan axis for which the absolute angle of the camera cannot be calculatedfrom the acceleration sensor 107 (such as a yaw rotation axis as arotation axis around the Y-axis direction in a case where the Y-axisdirection of FIG. 1B perfectly accords with the gravity direction). Anabsolute angle is calculated by the angular velocity integration duringa period in which the absolute angle of the camera cannot be calculated,by starting with the last absolute angle at which the absolute angle ofthe camera is determined to be calculable due to changes in the cameraangle.

A description will now be given of the calculating method of the imagestabilizing amount. The image stabilization can be performed by drivingthe tilt rotation unit 104 and the pan rotation unit 105 based on theabsolute angle of the camera calculated by the method described above.However, image stabilizing control based on the absolute angle of thecamera can provide control for continuing to maintain the sameorientation forever and thus the composition is not changed, forexample, in a case where the photographer captures an image whilemoving, and image stabilizing control becomes unavailable beyond amovable end of each unit. Accordingly, image stabilizing control isperformed for a high-frequency component without image stabilization fora low-frequency component. That is, the image stabilizing amount iscalculated using the angular velocity sensor 106 in order to performimage stabilizing control for the high-frequency component withoutperforming image stabilizing control for the low-frequency component.

The image stabilizing angle is calculated by integrating the output ofthe angular velocity sensor 106 after its DC component is cut with ahigh-pass filter (HPF) to convert it into an angular signal. A panimage-stabilizing angle calculating unit 705 calculates an imagestabilizing angle in the panning direction (yawing direction) from thegyro-yaw angular velocity output from the angular velocity sensor 106.The image stabilization is performed in the panning direction by drivingthe pan rotation unit 105 based on the calculated image-stabilizingangle. As for the tilting direction, since the angular velocity sensor106 is mounted on the fixing unit 103, the image stabilizing control inthe tilting direction changes depending on the rotation angle of the panrotation unit 105. In a case where the camera 101 is in the normalposition (the X-axis direction in FIG. 8A is always orthogonal to theoptical axis), the pitch image-stabilizing angle calculated by a pitchimage-stabilizing angle calculating unit 706 is directly used as thetilt image-stabilizing angle. In a case where the camera 101 is rotatedby 90 degrees from the normal position (the Z-axis direction in FIG. 8Bis always orthogonal to the optical axis), the roll image-stabilizingangle calculated by a roll image-stabilizing angle calculating unit 707is directly calculated as the tilt image-stabilizing angle. The tiltimage-stabilizing angle corresponding to the pan rotation angle iscalculated using the following expression (3).θtl=θpi×cos θap+θri×sin θap  (3)where θtl is a tilt image-stabilizing angle, θpi is a pitchimage-stabilizing angle, θri is a roll image-stabilizing angle, and θapis a pan rotation angle.

As described above, a tilt image-stabilizing angle calculating unit 704calculates the tilt image-stabilizing angle according to the panrotation angle.

The tilt image-stabilizing angle can be calculated by converting thepitch angular velocity and roll angular velocity from the angularvelocity sensor 106 and the tilt angular velocity calculated from thepan rotation angle (current position 708 of the pan rotation unit 105).

By the method described above, the pan image-stabilizing angle and thetilt image-stabilizing angle can be calculated, and the tilt rotationunit 104 and the pan rotation unit 105 are driven according to eachimage-stabilizing angle (image stabilizing amount) for imagestabilization.

The absolute angle of the barrel 102 can be calculated from the absoluteangle of the camera and the rotation angles of the tilt rotation unit104 and the pan rotation unit 105. More specifically, by subtracting therotation angle of the pan rotation unit 105 from the absolute yaw anglecalculated from the absolute yaw angle calculating unit 702, a cameraangle based on the optical axis in the yawing direction (absolute yawangle of the barrel 102) can be calculated.

The rotation angles of the barrel 102 in the pitch direction and rolldirection converted into the position of the fixing unit 103 can becalculated from the rotation angles of the pan rotation unit 105 and thetilt rotation unit 104. A camera angle based on the optical axis in thepitch direction (absolute pitch angle of the barrel 102) is calculatedby subtracting the rotation angle of the barrel 102 in the pitchdirection from the absolute pitch angle calculated from the absolutepitch angle calculating unit 701. A camera angle based on the opticalaxis in the roll direction (absolute roll angle of the barrel 102) iscalculated by subtracting the rotation angle of the barrel 102 in theroll direction from the absolute roll angle calculated from the absoluteroll angle calculating unit 703.

As described above, once the absolute angle of the camera can beacquired based on the optical axis, which angular direction the barrel102 faces can be determined, for example, based on the angle in a casewhere the camera is started.

After the absolute angle of the camera and the image stabilizing amountare calculated, the control unit 212 detects camera movement in stepS608. More specifically, the control unit 212 acquires information as towhether the camera 101 has significantly moved from the apparatusmovement detecting unit 209. The control unit 212 may use informationfrom an external device that can acquire GPS position information todetermine whether the camera 101 has significantly moved.

In step S609, the control unit 212 determines the camera state. Morespecifically, the control unit 212 determines what kind ofvibration/motion state the camera 101 is currently in based on thecamera angle, camera moving amount, and the like. For example, in a casewhere the camera 101 is attached to a car and captures an image, objectinformation such as surrounding landscapes significantly changes due tomovement and thus the control unit 212 determines whether the camera 101is in a “moving state on a vehicle” in which the camera 101 is mountedon a car or the like and is moving at a high speed. The determinationresult can be used for automatic object searching, which will bedescribed below. The control unit 212 determines, based on a change inthe camera angle, whether the camera 101 is in an “imaging state in theplacement” in which there is almost no shake angle of the camera. It canbe considered that the camera 101 has no angular change in the “imagingstate in the placement,” object search for imaging in the placement canbe performed. In a case where the camera has a relatively large angularchange, the control unit 212 determines that the camera is in a“handheld state” and object searching for the handheld state can beperformed.

In step S610, the control unit 212 determines whether the absolute angleof the camera is undetectable. The state in which the absolute angle ofthe camera is undetectable is, for example, a case where the camerareceives such a great impact that a problem occurs in the calculation ofthe absolute angle of the camera using the output of the accelerationsensor 107, or a case where the camera has such a high angular velocitythat it exceeds the detectable range of the angular velocity sensor 106.In a case where it is determined that the absolute angle of the camerais undetectable, the flow proceeds to step S611; otherwise, the flowproceeds to step S612. In step S611, the control unit 212 initializesautomatic object search processing.

In step S612, the control unit 212 performs area division based on theabsolute angle of the camera at the initial setting in step S601 or inthe initialization of the automatic object search processing in stepS611. In addition, the control unit 212 divides the image currentlyacquired by the camera 101 into blocks based on the area division.

The area division will be described below with reference to FIGS. 9A to9D. FIGS. 9A to 9D explain the area division. As illustrated in FIG. 9A,the area division is performed over the whole circumference around theposition of the camera 101 represented by an origin O as the center. InFIG. 9A, the area is divided every 22.5 degrees in each of the tiltingdirection and the panning direction. In the case where the area isdivided as illustrated in FIG. 9A, as the angle in the tilting directionbecomes higher from 0 degrees, the circumference in the horizontaldirection becomes smaller and the area becomes smaller. Thus, asillustrated in FIG. 9B, in a case where the tilt angle is 45 degrees ormore, the horizontal area is set to have an angle larger than 22.5degrees.

FIG. 9C illustrates an example of area division within a captured angleof view. A direction 901 is a direction of the camera 101 duringinitialization, and area division is performed based on the direction901. Reference numeral 902 denotes a view angle area of the capturedimage, and FIG. 9D illustrates an example of an image at that time. Theimage captured at this angle of view is divided as illustrated byreference numerals 903 to 918 in FIG. 9D based on the area division.

FIGS. 10A to 10C explain area division within a captured image, which isarea division within an imaging angle of view where the panningdirection of the camera 101 is the direction 901. FIG. 10A illustratesan area based on the absolute angle of the camera 101 duringinitialization of automatic object searching, in which reference numeral1001 denotes the imaging angle of view and reference numeral 1002denotes a center of the angle of view where the tilt angle is 0 degrees.FIG. 10B illustrates the captured image at that time. In FIG. 10A,reference numeral 1003 denotes an imaging angle of view, and referencenumeral 1004 denotes a center of the angle of view where the tilt angleis 55 degrees. FIG. 10C illustrates the captured image at that time.

In a case where the tilt angle is 0 degrees, an angular range in thelateral (horizontal) direction does not significantly change, so adifference in area size is small, but in a case where the tilt angle is55 degrees, an angular range in the lateral direction will significantlychange depending on the angle. Therefore, in a case where the tilt angleis 45 degrees or higher, the area in the horizontal direction is set tohave an angle larger than 22.5 degrees. Thereby, the area is preventedfrom becoming too small as the tilt angle increases.

FIGS. 11A and 11B explain area division in a captured image. FIG. 11Aillustrates an area in a case where the camera 101 is rotated by 11.25degrees in the panning direction from the initial position, referencenumeral 1101 denotes an imaging angle of view and reference numeral 1102denotes a center of the angle of view where the tilt angle is 0 degrees.FIG. 11B illustrates a captured image at that time. As illustrated inFIG. 11A, an area is set around 11.25 degrees in the horizontaldirection as a center.

The area within the above imaging angle of view is calculated by thefollowing expressions (4) and (5), all the areas existing within theangle of view are calculated, and the area is divided within the image:θay=θy+θy′  (4)θax=θx′·cos θay  (5)where θy is a tilt angle based on the initial position of the camera101, θx′ is an angle from the pan angle position (horizontal center ofthe image) to an area division angle, θy′ is an angle from the tiltangle position (vertical center of the image) to an area division angle,θax is a length of the horizontal angle from the horizontal center tothe horizontal area division angle in the image, and θay is a length ofthe vertical angle from the vertical center to the vertical areadivision angle in the image. The initial position of the camera 101 isset to 0 degrees.

The area division angle is set every 22.5 degrees, but the horizontalarea division is set to 45 degrees in a range of 45 degrees to 67.5degrees in the vertical direction. No horizontal division is made in arange of 67.5 degrees to 90 degrees in the vertical direction and thearea is set to a single area.

In step S613, the control unit 212 calculates the importance level. Asillustrated in FIG. 9D, the importance level is calculated for each areabased on object information and the like in the acquired image. However,in a case where the captured area is small relative to the angle of view(for example, in a case where the area size is set to 100%, a capturedarea in the image is 50% or less), no importance level is determined orupdated. The importance level is set according to various conditions foreach set area.

Importance Level Setting According to Personal Information

The importance level is set according to personal information in eacharea within an angle of view. A face detecting method includes, forexample, a method that uses knowledge about faces (skin colorinformation, parts information such as eyes, nose, and mouth) and amethod that constitutes an identifier unit for face detection using alearning algorithm represented by a neural network. It is general toperform face detection by combining a plurality of face detectionmethods in order to improve detection accuracy. By performing the facedetection, the size and orientation of a face, and the credibilityrepresenting the certainty of a face, etc., are calculated. There isalso a known method of detecting a facial expression from detectioninformation for each organ of the face, and using this method can detectthe opening degree of the eyes and the smiling degree. Morespecifically, this method acquires feature amounts necessary to detectthe facial expression based on the contours of the facial organs (eyes,nose, mouth, etc.) and positions of inner and outer corners of eyes,nose wings, corners of a mouth, lips, and the like. The acquiring methodof the feature amounts includes a template matching method usingtemplates of each facial component, a learning algorithm method using alarge number of sample images of facial components, and the like. Basedon the detected feature amounts, this method can detect facialexpressions such as smiling degree, blink, wink, and facial expressionestimation (such as joy, surprise, anger, sadness and seriousness).

Personal face data are previously registered, and personal faceauthentication can be performed to detect whether the detected face is aspecific individual. Whether or not the state matches a targetpreviously registered in a database or the matching degree isdetermined. The object area and feature information for identifying theobject to be authenticated are extracted based on the image data of thedetected object, and the extracted feature information and the featureinformation on the image of the object previously registered in thedatabase are compared with each other. Based on an authenticationevaluation value that represents the similarity degree obtained by thecomparison, authentication is made as to which registered object theobject to be authenticated is or whether there is no correspondingregistered object. For example, in a case where the authenticationevaluation value is equal to or higher than a predetermined threshold,it may be determined that the object to be authenticated is a targetregistered in the database.

Kr is a value of the level set by face credibility (for example, whichincreases from low credibility to high credibility). The credibility isdetermined by the size and orientation of the face, the certainty of theface, and the like. Ka is a value of the level set by personal faceauthentication information and is set for each face based on theimportance level for each registered personal face (where the importancelevel is previously registered) and past imaging information, which willbe described below. Ks is a value of the level set according to facialexpression and is rated for each face based on a level corresponding topreset facial expression (for example, smile, joy, surprise, and thelike are given a high level, whereas anger, sadness, seriousness, blink,and the like are given a low level). The level may be variable accordingto the facial expression degree for each facial expression, such as thesmiling degree in the case of a smile.

From the values Kr, Ka, and Ks, a level Flvl corresponding to thepersonal face expression is expressed by the following expression (6).Flvl=Kr·Ka·Ks  (6)

Referring now to FIG. 12 , a description will be given of the importancelevel setting according to personal information. FIG. 12 explains persondetection for each area in a captured image. For a small areaillustrated in an image, such as areas 1201, 1204, 1205, and 1208, it isnot determined as not being searched. A description will now be given ofa case where three persons (1209, 1210, 1211) are captured within anangle of view as an example. Assume that the person 1209 is an objectthat has not yet been registered as personal face authentication and hasno smiling face. The person 1210 is an object that has not yet beenregistered as personal face authentication and has a smiling face. Theperson 1211 is an object that has been registered as personal faceauthentication and has a smiling face.

Since the person 1209 is captured in areas 1202 and 1206, levels of bothareas are set according to the personal information on the person 1209.The value (gain) Ka is 1 because the person 1209 has not yet beenregistered as individual authentication when the registered individualauthentication information is referred to, the value (gain) Ks is 1because the person 1209 is not smiling, and thus the level Flvl of theperson 1209 is Kr.

Since the persons 1210 and 1211 are captured in areas 1203 and 1207,importance levels are set to both areas according to the personalinformation on the persons 1210 and 1211. The person 1210 has a value Kaof 1 because it has not yet been registered as personal faceauthentication, and a value Ks of 1 or higher because the object has thesmiling face. Since the person 1211 has been registered as personal faceauthentication, the value Ka is 1 or higher, and since the object has asmiling face, the value Ks is 1 or higher. In a case where the persons1209, 1210, and 1211 have the same face credibility, they areprioritized in the order of the persons 1211, 1210, and 1209.

The level is set according to the facial ratio in the image. Thecalculated importance level is set as it is for areas having largefacial ratios, and the importance level is changed according to thefacial ratio for areas having small facial ratios. For example, in acase where the facial ratio of a person between the areas 1203 and 1207is 8:2, the importance level is set to 10:2.5.

As described above, the importance level is set for each area based onpersonal face information.

Importance Level Setting According to Object Recognition Information

In a case where a previously registered object is detected, theimportance level is set according to object recognition information. Forexample, general object category recognition such as “dog” and “cat” isperformed, and the importance level is set according to objectrecognition and the matching degree with a previously registered objectimage. The object recognition includes a method that constitutes anidentifier unit for “dog”, “cat”, etc. using a learning algorithmrepresented by a neural network.

Referring now to FIG. 13 , a description will be given of the importancelevel setting according to previously registered object recognitioninformation. FIG. 13 explains object detection for each area in acaptured image. A description will now be given of a case where threeobjects (1309, 1311, 1313) are captured within an angle of view as anexample. The objects 1309 and 1313 are determined to be a dog and a cat,respectively, by the object recognition. The object 1311 is a person,and the person is determined by the importance level setting accordingto personal information and thus is not an object for the purpose of theimportance level setting according to the object recognitioninformation. Assume that the level in a case where a “dog” is recognizedand the level in a case where a “cat” is recognized are registeredrespectively. For example, in a case where the “dog” is set as animportant object and the “cat” is not set as an important object, thearea 1307 where the “dog” is detected has a higher importance level thanthat of the area 1306 where the “cat” is detected.

The importance level may be changed according to the credibility ofobject recognition. For example, the level is set according to the ratioof the object being imaged. The calculated importance level is set as itis for an area having the largest object ratio, and the importance levelis changed according to the object ratio for an area having a smallobject ratio.

Importance Level Setting According to Scene

By analyzing image data, a “blue sky scene,” a “natural green scene,” a“evening view,” and the like are determined, and a level is set based onthe scene determination information. In the scene determinationregarding the sky, the tilt information on the camera 101 can beobtained from the absolute angle information on the camera 101 and “bluesky scene,” “evening view,” and the like can be determined using animage in an area above a direction perpendicular to the gravitydirection the like.

First, 12-bit RAW data of one captured frame is divided into n×m areablocks (where n and m are integers), and an average value of the R, G,and B pixels in each divided area is calculated. White balancecorrection processing, gamma correction processing, and provisionaldevelopment processing by color conversion matrix processing areperformed for the R, G, and B average values of each block.

The “blue sky scene” is determined by calculating the ratio of blue skyblocks in the upper area in an image. Determination of whether or not ablock is a blue sky block is made by defining a blue sky determinationarea in the UV color space and by counting the number of blocksbelonging to that area. The “evening view” determination is made bycalculating a ratio of evening view blocks in the upper area in animage. Determination of whether or not a block is an evening view blockis made by defining an evening view determination area in the UV colorspace and counting the number of blocks belonging to that area.Determination of the “natural green scene” is made by detecting a ratioof natural green blocks to all blocks in an image. A determination as towhether or not a block is a natural green block is made by defining anatural green determination area in the UV color space and by countingthe number of blocks belonging to that area.

Referring now to FIG. 14 , a description will be given of importancelevel setting according to scene detection information. FIG. 14 explainsscene detection for each area in a captured image. In FIG. 14 , the bluesky is captured in the upper right area of the image, a building iscaptured in the left area of the image, and natural green is illustratedin the lower right area of the image. The “blue sky scene” and the“natural green scene” are detected by scene determination in the image,and the level of an area 1403 is set according to the blue sky arearecognition, and the level of an area 1407 is set according to thenatural green area recognition. An area 1402 has a blue sky area ofabout 40% of the entire area, and is given 40% of the level setaccording to the blue sky area recognition. An area 1406 has a naturalgreen area of about 30% of the entire area, is given 30% of the levelset according to the natural green area recognition.

Although the scene determination method based on the color spaceinformation has been described above, there is also a method fordetermining a scene based on a luminance value, which will be describedwith “evening view” determination as an example. In a case where thehistogram of the entire image has a distribution of extremely highluminance levels and extremely low luminance levels, the image isdetermined as a night scene. Alternatively, a point light source may bedetermined by contrast evaluation based on a high-frequency component ofa luminance signal of an image, and the “night scene” may be determinedbased on the luminance distribution and the point light source detectionresult.

Importance levels for the “blue sky scene,” the “evening view,” the“natural green scene,” and the “night scene” are registeredrespectively, and the importance level is set according to the scene foreach area and the registered importance level.

Importance Level Setting According to Sound Information

By analyzing sound information data, a “sound direction”, a “soundlevel”, “sound recognition”, and the like are determined, and theimportance level is set based on the sound information. Referring now toFIG. 15 , a description will be given of importance level settingaccording to sound information. FIG. 15 is a flowchart for explainingsound detection.

In step S1501, a sound acquiring unit included in the control unit 212determines whether or not the sound generated outside has been acquired.In a case where it is determined that the sound has been acquired, theflow proceeds to step S1502; otherwise, this step is repeated.

In step S1502, a sound direction detecting unit included in the controlunit 212 detects the direction of the acquired sound. In step S1503, thesound level is detected. In step S1504, a sound recognition unitincluded in the control unit 212 recognizes the acquired sound. In stepS1505, it is determined whether the acquired sound is a predeterminedsound command for sound recognition. In a case where it is determined tobe the sound command, the flow proceeds to step S1506; otherwise, theflow proceeds to step S1507. In step S1506, sound recognition level Scof the acquired sound is set to Ac1. In step S1507, the soundrecognition level Sc of the acquired sound is set to zero.

In step S1508, it is determined whether the detected sound level isequal to or higher than a predetermined value. In a case where it isdetermined to be equal to or higher than the predetermined value, theflow proceeds to step S1509; otherwise, the flow proceeds to step S1510.In step S1509, sound level Ss is set to Ac2. In step S1510, the soundlevel Ss is set to zero.

In step S1511, a sound direction area is calculated from the soundgenerating direction detected in step S1502. For example, considering asound direction recognition error, the sound direction area is set to anentire range of ±45 degrees from the determined direction angle. In stepS1512, the sound recognition level Sc and the sound level Ss are addedto calculate total sound level Sl. In step S1513, it is determinedwhether or not the total sound level Sl has increased from the totalsound level Sl at the previous sampling. In a case where it isdetermined that the value has increased, the flow proceeds to stepS1514; otherwise, the flow proceeds to step S1516. In step S1514, timecount Xt is set to predetermined time Ta. In step S1515, the level Sl isset to the sound direction area calculated in step S1511. In step S1516,the predetermined time Ta is decremented. In step S1517, it isdetermined whether the predetermined time Ta is 0 or less. In a casewhere it is determined to be 0 or less (in a case where thepredetermined time Ta has passed since the level Sl changed toincrease), the flow proceeds to step S1518; otherwise, the flow proceedsto step S1516. In step S1518, 0 is set in the sound direction areacalculated in step S1511.

Importance Level Setting According to Image Motion Information

It is determined whether or not a moving object exists in each areadivided as illustrated in FIGS. 9A to 9D, and the importance level isset according to the image motion information.

Difference detection between frames and motion vector detection betweenframes are performed for each area. The motion vector detecting methodincludes a method of calculating an image motion amount from relativeshift information on an image by dividing the image into a plurality ofareas, and by comparing a previously stored image of the last frame (oneframe before) with the current image (two consecutive images).

Here, the angle of the barrel 102 (in the optical axis direction on theimage plane) is known from a difference between the absolute angle ofthe camera and the rotation positions of the tilt rotation unit 104 andthe pan rotation unit 105. Therefore, the motion vector value of theimage blur caused by the influence of the camera angle change can bedetectable from the difference in the angle of the barrel 102 betweenframes. FIGS. 16A to 16C explain motion detection in a captured image.As illustrated in FIG. 16A, moving pixels between frames are detected infurther divided areas in each area, and frequency distributionprocessing is performed with a vector signal obtained by subtracting themotion vector value due to the influence of camera angle change from thedetected moving pixels. In a case where vector detection is difficultdue to low contrast or the like, the vector information on theundetectable blocks is not reflected on the frequency distributionprocessing. FIG. 16B illustrates a frequency distribution example in acertain frame in a case where no moving object exists in a certain area.Since a threshold 1602 is a vector range with small vector values andalmost no movement, the vector information within the threshold 1602 isnot used. In a case where a moving amount other than the threshold 1602exceeds a threshold 1603, it is determined that the moving object existsin the area. Since the moving amount does not exceed the threshold 1603in FIG. 16B, it is determined that there is no moving object. FIG. 16Cillustrates a frequency distribution example in a frame in which amoving object exists in an area. Since a vector moving amount outsidethe threshold 1602 exceeds the threshold 1603, it is determined that amoving object exists in this area. In a case where it is determined thatthe moving object continuously exists for the past several frames, theimportance level corresponding to the moving object existing is set.

Importance Level Setting According to Past Imaging Information

The importance level is set based on past imaging information. In a casewhere the camera 101 detects an automatic imaging trigger from the imageinformation being searched in the automatic object searching, automaticimaging is performed. The automatic imaging trigger may be, for example,the detection of facial expressions such as a smile of a person, or themagnitude of the final importance level. The photographer may manuallycapture an image using a release switch SW or the like provided on thecamera 101. In a case where the camera 101 captures an image, pastimaging information is stored and managed.

First, the level setting according to the past imaging information foreach area will be explained. As illustrated in FIGS. 9A to 9D, in eachdivided area, the number of captured images in each area is stored andmanaged. FIG. 17 explains the management of the number of capturedimages for each area. The importance level for each area is set from thepast information for each area illustrated in FIG. 17 . “Now to T1hours” indicates the number of captured images from the present to T1hours ago, and a weighting factor for this period is set to 1, forexample. “T1 hours to T2 hours” indicates the number of captured imagesfrom T1 hours ago to T2 hours ago, and a weighting factor for thisperiod is set to 0.8, for example. “T2 hours to T3 hours” indicates thenumber of captured images from T2 hours ago to T3 hours ago, and aweighting factor for this period is set to 0.5, for example. “T3 hoursto T4 hours” indicates the number of captured images from T3 hours agoto T4 hours ago, and a weighting factor for this period is set to 0.2,for example. The weighted total number of captured images is calculatedfor each area by multiplying each weighting factor by the number ofcaptured images and by adding the calculation results at each time. Theweighted total number of captured images for Area1 is 0.4(=0×1+0×0.8+0×0.5+2×0.2), and the weighted total number of capturedimages for Area3 is 7.2 (=3×1+4×0.8+2×0.5+0×0.2). The level is setaccording to the past imaging information for each area by multiplyingthe weighted total number of captured images for each area by a levelcoefficient, which is a negative value and set so that the importancelevel decreases as the number of captured images increases. The pastimaging information is also fed back to the “IMPORTANCE LEVEL SETTINGACCORDING TO PERSONAL INFORMATION,” the “IMPORTANCE LEVEL SETTINGACCORDING TO OBJECT RECOGNITION INFORMATION,” the “IMPORTANCE LEVELSETTING ACCORDING TO SCENE,” and the like and also affects each level.

FIG. 18 explains the management of the number of captured images foreach registered object that has received personal authentication, and isa table that manages the past imaging information for feeding back tothe “IMPORTANCE LEVEL SETTING ACCORDING TO PERSONAL INFORMATION.” Thenumber of past captured images for each of personally registered objects(Asan, Bsan, Csan, Dsan, . . . ) is stored and managed. As in the methoddescribed with reference to FIG. 14 , a weighting factor is set for eachtime, and the total number of captured images is calculated for eachregistered object. By adding the result obtained by multiplying thetotal number of captured images by a level coefficient for the levelsetting to the value Ka, the past imaging information is fed back to the“IMPORTANCE LEVEL SETTING ACCORDING TO PERSONAL INFORMATION.” The levelcoefficient is a negative value, and the level decreases as the numberof captured images increases. The value Ka is set so as not to become 0or less.

FIG. 19 explains the management of the number of captured images foreach registered object that has been recognized as an object, and is atable for managing the past imaging information for feeding back to the“IMPORTANCE LEVEL SETTING ACCORDING TO OBJECT RECOGNITION INFORMATION.”The number of past captured images for each registered object (such as adog and a cat) is stored and managed. As in the method described withreference to FIG. 14 , a weighting factor is set for each time, and thetotal number of captured images is calculated for each registeredobject. By adding the result obtained by multiplying the total number ofcaptured images by a level coefficient for the level setting to thelevel according to each object, the past imaging information is fed backto the “IMPORTANCE LEVEL SETTING ACCORDING TO OBJECT RECOGNITIONINFORMATION.” The coefficient is a negative value, and the leveldecreases as the number of captured images increases. The importancelevel corresponding to each object is set so as not to become 0 or less.

FIG. 20 explains the management of the number of captured images foreach scene, and is a table for managing the past imaging information forfeeding back to the “IMPORTANCE LEVEL SETTING ACCORDING TO SCENE.” Thenumber of past captured images for each scene (blue sky, evening view,natural green, night view, etc.) is stored and managed. As in the methoddescribed with reference to FIG. 14 , a weighting factor is set for eachtime, and the total number of captured images is calculated for eachregistered object. By adding the result obtained by multiplying thetotal number of captured images by a level coefficient for the levelsetting to the level according to each scene, the past imaginginformation is fed back to the “IMPORTANCE LEVEL SETTING ACCORDING TOSCENE.” The coefficient is a negative value, and the level decreases asthe number of captured images increases. The importance level accordingto each scene is set so as not to become 0 or less.

Importance Level Setting According to Unsearched Time

As illustrated in FIGS. 9A to 9D, the importance level is set accordingto the elapsed time after the last search at each divided area position.FIG. 21 is a flowchart for explaining calculation based on the elapsedtime after the last search. In step S2101, the current pan/tiltpositions are acquired. In step S2102, the absolute angle of the camerais calculated in the manner described with reference to FIGS. 9A to 9D.In step S2103, the absolute angle of the barrel 102 is calculated fromthe pan/tilt positions acquired in step S2101 and the absolute angle ofthe camera acquired in step S2102.

In step S2104, 1 is substituted for Area, which is a variable for loopoperation. In step S2105, it is determined whether the absolute angularvelocity calculated by differentiating the absolute angle of the barrel102 falls within a predetermined velocity range and the variable Areafalls within the angle of view. Here, the predetermined velocity rangeis a velocity range in which the object can be detected at the absoluteangular velocity (angular velocity range within a predetermined value ofdelay time until the object is detected from the image while the imagingdelay and the detection time delay are considered). In a case where itis determined that the absolute angular velocity is within thepredetermined velocity range and the variable Area is within the angleof view, the flow proceeds to step S2106. Otherwise, the flow proceedsto step S2107. In step S2106, the importance level according to theunsearched time of the current variable Area is set to zero. In stepS2107, the time level of the current variable Area is incremented. Instep S2108, the variable Area is incremented. In step S2109, it isdetermined whether the variable Area is larger than the number of totalareas. In a case where it is determined that the variable Area is largerthan the number of total areas, this flow is terminated; otherwise, theflow returns to step S2105.

The above method sets the importance level according to the unsearchedtime for each area. The time level of each area increases according tothe elapsed time after the area was last searched for objects(unsearched time of the area). Thereby, in a case where there is an areathat has not been searched for a long time, the importance levelincreases and the area is searched by panning/tilting.

Importance Level by Camera Vibration State

The importance level is set according to the camera vibration state. Thevibration state of the camera 101 (vehicle detection state, imagingstate in the placement, and handheld state) is determined from thecamera state determined in step S609 of FIG. 6 .

In a case where the vibration state of the camera 101 is the “imagingstate in the placement”, no erroneous calculation of the absolute angleof the camera occurs and the calculation credibility of the importancelevel of each area is high. Thus, subsequent search control is made byusing the importance level of each area as it is.

In a case where the vibration state of the camera 101 is in the “vehicledetection state,” the moving velocity is high. Thus, the area of theperson riding the vehicle hardly changes, but an object such as alandscape changes moment by moment. Therefore, in the case of the“vehicle detection state,” the “IMPORTANCE LEVEL SETTING ACCORDING TOPERSONAL INFORMATION” uses the importance level as it is, but theimportance level of the “IMPORTANCE LEVEL SETTING ACCORDING TO IMAGEMOTION INFORMATION” is not used. Since the “IMPORTANCE LEVEL SETTINGACCORDING TO SCENE” and the “IMPORTANCE LEVEL SETTING ACCORDING TOOBJECT RECOGNITION INFORMATION” may change soon, the importance level isreduced. However, the automatic imaging may be modified so that imagingis performed as soon as the object is detected. Each of the “IMPORTANCELEVEL SETTING ACCORDING TO SOUND INFORMATION” and the “IMPORTANCE LEVELSETTING ACCORDING TO PAST IMAGING INFORMATION” uses the importance levelas it is. A traveling direction of the camera 101 is detected, thetraveling direction in which the camera 101 is moving at a high velocityis detected by an acceleration sensor or the like, and calculation isalso performed such as increasing the importance level of the area inthe traveling direction.

In a case where the vibration state of the camera 101 is the “hand-heldstate” (state of large vibration), the photographer is highly likely tooperate the direction of the camera 101. Accordingly, the importancelevel for each area is set as follows: The importance level is set highfor an area in a range of ±45 degrees from the camera normal position(at which the tilt angle and pan tilt angle are 0 degrees), and theimportance level is set low for an area in a range of ±45 degrees to ±90degrees. The importance level is set lower for an area in a range ofhigher than ±90 degrees. A method of adding the importance level foreach area may be used, or a method of weighting the importance levelcalculated for each area according to the range may be used. Theweighting factor is set to 1 for the area within the range of ±45degrees, the weighting factor is set to 1 or less for the area withinthe range of ±45 degrees to ±90 degrees, and the weighting factor is setlower for the range of higher than ±90 degrees.

The above method changes the importance level calculation according tothe vibration state of the camera 101 so as to search the objectaccording to the vibration state.

After the importance level of each area obtained by the above method iscalculated, the flow proceeds to step S614.

Calculation of Target Angles for Pan/Tilt Searching

In step S614, the control unit 212 calculates target angles for pan/tiltsearching from the importance level for each area. The target angles forthe pan/tilt searching are calculated by the following method.

First, a final search level is calculated based on the importance levelsof areas adjacent to each area. FIGS. 22A and 22B explain searchingtarget angle calculation for each scene. The final search level in anarea 2201 of FIG. 22A is calculated based on information on the area2201 and surrounding areas. A weighting factor for the area 2201 is setto 1 and the other weighting factors are set to 1 or less (for example,0.5). Then, the final search level is calculated by multiplying theimportance level of each area by the weighting factor, and by adding upthe calculated values acquired for all areas. This calculation isperformed for all areas to calculate the final search level in eacharea.

Next, an area having the highest final search level is set to thesearching target area. In a case where the searching target area is thearea 2201 in FIGS. 22A and 22B, the target angles for the pan/tiltsearching are calculated from the final search levels of the areas 2201to 2209 and the central angles of the areas 2201 to 2209 by thefollowing expression (7):

$\begin{matrix}{y = {{\sum}_{i = 1}^{n}\left( {b_{i} \times \frac{a_{i}}{{\sum}_{i = 0}^{n}a_{i}}} \right)}} & (7)\end{matrix}$where n is the number of areas, i is a variable defining each area as 1to 9, b is a central angle of each area, and a is a final search levelof each area. Thus, the target angles y for the pan/tilt searching iscalculated by calculating the center-of-gravity position y of the anglebased on the calculated final search levels among the areas 2201 to 2209(while y is calculated for each of the tilting direction and the panningdirection). In a case where all the values of the final search levels ofrespective areas are equal to or less than a predetermined threshold, itis determined that there is no important object at that time even if thesearch is performed and no pan or tilt driving is performed. At thistime, the target angle is calculated based on the importance levelcalculated under the conditions excluding the “IMPORTANCE LEVEL SETTINGACCORDING TO PAST IMAGING INFORMATION,” and after the camera is pannedand/or tilted to the target angle, the angular position is maintaineduntil any one of the final search levels of the respective areas islarger than the predetermined threshold.

The target angles for the pan/tilt searching are calculated as describedabove, and the flow proceeds to step S615.

Calculation of Pan/Tilt Driving Amounts

In step S615, the control unit 212 calculates the pan/tilt drivingamounts based on the image stabilizing amount acquired in step S607 andthe target angles for the pan/tilt searching acquired in step S614. Byadding a driving angle in control sampling based on the imagestabilizing amount and the target angles for the pan/tilt searching,pan/tilt driving amounts (pan driving angle and tilt driving angle) arecalculated.

Pan/Tilt Driving

In step S616, the control unit 212 controls driving of the tilt rotationunit 104 and the pan rotation unit 105 via the barrel rotation drivingunit 112 according to the pan/tilt driving angles.

Updating Past Imaging Information

In step S617, the past imaging information is updated.

Determining Method of Voltage Amplitude According to Phase Difference

A description will now be given of a method of controlling (determining)a voltage amplitude according to a phase difference between voltagesapplied to the vibrator 1052 in controlling driving of the pan rotationunit 105. Here, for controlling driving of the pan rotation unit 105 ata low velocity, a phase difference control mode is suitable thatcontrols the velocity by changing the phase difference while fixing thefrequency of the voltages applied to the vibrator 1052. FIG. 23illustrates an example of a relationship between the phase differencebetween the voltages applied to the vibrator 1052 and the voltageamplitude. In FIG. 23 , a horizontal axis represents the phasedifference, and a vertical axis represents the voltage amplitude.

In a case where the phase difference has a value (=zero) represented bya dotted line P0, the voltage amplitude has a lower limit value Dmin. Ina case where the phase difference is increased so as to increase thedriving velocity, the voltage amplitude has conventionally been linearlyincreased, as indicated by a broken line 2301.

FIGS. 24A to 24C illustrate a relationship between the phase differencebetween the voltages applied to the vibrator 1052 and the drivingvelocity depending on a difference in the voltage amplitude. In FIGS.24A to 24C, a horizontal axis represents the phase difference, and avertical axis represents the driving velocity. FIG. 24A illustrates arelationship between the phase difference and the driving velocity in acase where the voltage amplitude is set to be sufficiently large,illustrating that the driving velocity changes as the phase differencechanges. FIG. 24B illustrates a relationship between the phasedifference and the driving velocity in a case where the voltageamplitude is set near the lower limit value Dmin. In a range where theabsolute value of the phase difference is small, the change in thedriving velocity does not follow the change in the phase difference, andthis range causes a wide dead zone in velocity control. That is, itindicates that the velocity controllability is lowered in the case wherethe voltage amplitude is set near the lower limit value Dmin.

The conventional method of increasing the voltage amplitude in a linearrelationship with the phase difference as illustrated by the broken line2301 in FIG. 23 takes time until the change in the driving velocityfollows the change in the phase difference beyond the dead zone of thevelocity control, because the change rate of the voltage amplitude isconstant. Accordingly, in a case where this embodiment increases thephase difference in order to increase the driving velocity, thisembodiment increases the voltage amplitude so that the smaller theabsolute value of the phase difference is, the higher the change rate ofthe voltage amplitude becomes, as indicated by a solid line 2302 in FIG.23 . More specifically, a voltage amplitude k is changed based on a sinewave function as expressed by the following expression (8).

$\begin{matrix}{k = {{D\min} + {\left( {{D\max} - {D\min}} \right){\sin\left( {\frac{Phase}{Phase\_ max}\frac{\pi}{2}} \right)}}}} & (8)\end{matrix}$where Dmin is the lower limit of the voltage amplitude (voltageamplitude in a case where the phase difference is zero), Dmax is theupper limit of the voltage amplitude, Phase is the phase difference, andPhase_max is the maximum phase difference (90° in this embodiment).

The change rate k′ of the voltage amplitude is represented by thefollowing expression (9), and the smaller the absolute value of thephase difference is, the higher the change rate of the voltage amplitudebecomes.

$\begin{matrix}{k^{\prime} = {\frac{\left( {{D\max} - {D\min}} \right)}{Phase\_ max}\frac{\pi}{2}{\cos\left( {\frac{Phase}{Phase\_ max}\frac{\pi}{2}} \right)}}} & (9)\end{matrix}$

The configuration according to this embodiment can narrow the dead zoneof the velocity control in a range where the absolute value of the phasedifference is small, as illustrated in FIG. 24C, and suppress thedeterioration of the velocity controllability near the lower limit ofthe voltage amplitude.

FIG. 25 is a flowchart for explaining a method of controlling(determining) the voltage amplitude according to the phase difference incontrolling driving of the pan rotation unit 105.

In step S2501, the target position setting unit 1123 acquires a targetpan rotation position based on the rotation instruction from theoperation unit 211. The current position of the rotating unit 1051 isobtained from the position calculating unit 1122.

In step S2502, it is determined whether a difference between the currentposition and the target position of the pan rotation unit 105 is largerthan the smallest driving amount α. The smallest driving amount α may beset based on the calculation accuracy of the position calculating unit1122, or may be set based on a minimum value that causes no overrun indriving the pan rotation unit 105 while the difference between thecurrent position and the target position of the pan rotation unit 105 ischanged. The smallest driving amount α may be changed according to thefocal length of the zoom unit 201. In a case where it is determined thatthe difference between the target position and the current position islarger than the smallest driving amount α, the flow proceeds to stepS2503; otherwise, this flow ends.

In step S2503, the driving velocity of the pan rotation unit 105 iscalculated from the automatic object search condition.

In step S2504, the conversion unit 1127 calculates the phase differencebetween the two-phase voltages and the frequency using the controlamount calculated by the PID calculating unit 1124 based on thedeviation between the target position and the current position based onthe driving velocity calculated in step S2503.

In step S2505, the conversion unit 1127 calculates the (voltage)amplitude of the two-phase voltages according to the phase differencecalculated in step S2504 using the relationship indicated by the solidline 2302 in FIG. 23 .

In step S2506, the driving signal generating circuit 1128 generates thedriving signal corresponding to the two-phase voltages of the voltageamplitude calculated in step S2505 using the phase difference andfrequency calculated in step S2504, and outputs the driving signal todriving circuit 1054.

As described above, the configuration according to this embodimentincreases the change rate of the voltage amplitude as the absolute valueof the phase difference between the voltages applied to the vibrationwave motor decreases. Thereby, this embodiment can secure the controlperformance of the vibration wave motor while reducing the driving noisecaused by unnecessary vibrations in driving the vibration wave motor atlow velocity.

Voltage Amplitude Determining Method Using Phase Difference-DrivingVelocity Characteristic

The method for controlling (determining) the voltage amplitude based onthe sine wave function has been described, but a relationship betweenthe phase difference between the voltages applied to the vibrator 1052and the driving velocity is affected by the friction and the drivingload of the driving unit and thus is changed according to operationenvironments and individual differences. Accordingly, the relationshipbetween the phase difference between the voltages applied to thevibrator 1052 and the driving velocity may be measured, and the voltageamplitude may be controlled (determined) based on the phasedifference-driving velocity characteristic obtained from the measurementresult.

FIG. 26 is a block diagram of the pan rotation unit 105 and the barrelrotation driving unit 112. A velocity detecting unit (first detectingunit) 1129 detects the driving velocity from the change amount in thecurrent position acquired by the position calculating unit 1122. A phasedifference-velocity detecting unit (second detecting unit) 1130 detectsthe relationship between the phase difference calculated by theconversion unit 1127 and the driving velocity detected by the velocitydetecting unit 1129. Since other configurations are similar to thosedescribed with reference to FIG. 3 , a detailed description thereof willbe omitted.

FIG. 27 illustrates an example of measurement data of the phasedifference and the driving velocity detected by the phasedifference-velocity detecting unit 1130 in a case where the voltageamplitude of the voltages applied to the vibrator 1052 is set to thelower limit value Dmin while the phase difference is changed in apredetermined range (0° to 30° and 0° to −30° in this embodiment). InFIG. 27 , a horizontal axis represents the phase difference, and avertical axis represents the driving velocity.

Based on the measurement data detected by the phase difference-velocitydetecting unit 1130, a range in which the driving velocity does notexceed a predetermined value even if the phase difference changes is setto the dead zone, and the width and central value (central phasedifference) of the dead zone are calculated and stored. From themeasurement data, the change rate of the driving velocity (phasedifference-velocity characteristic) at each phase difference iscalculated and stored. In a case where the phase difference is includedin the dead zone in driving the pan rotation unit 105, the voltageamplitude is controlled (determined) according to a difference betweenthe phase difference and the central value of the dead zone and areciprocal of the change rate of the driving velocity. Since the changerate of the voltage amplitude is increased as the change rate of thedriving velocity decreases, the dead zone of the velocity control can benarrowed, and the deterioration of the velocity controllability can besuppressed near the lower limit of the voltage amplitude.

FIG. 28 is a flowchart for measuring and storing the phasedifference-velocity characteristic. The phase difference-velocitycharacteristic is measured and stored in initializing the tilt rotationunit 104 and the pan rotation unit 105 in the processing of step S601described with reference to FIG. 6 .

In step S2801, a phase difference (0° in this embodiment) for startingthe measurement of the phase difference-velocity characteristic is set.The voltage amplitude is set to the lower limit value Dmin.

In step S2802, the phase difference-velocity detecting unit 1130 detectsthe change rate of the driving velocity corresponding to each phasedifference from the driving velocity corresponding to each phasedifference detected by the velocity detecting unit 1129.

In step S2803, it is detected whether the set phase difference is thephase difference that ends the measurement of the phasedifference-velocity characteristic (30° or −30° in this embodiment). Ina case where it is determined that the set phase difference is the phasedifference that ends the measurement of the phase difference-velocitycharacteristic, the flow proceeds to step S2805; otherwise, the flowproceeds to step S2804.

In step S2804, the phase difference is changed.

In step S2805, the driving velocity and the change rate of the drivingvelocity corresponding to each phase difference are associated with theset phase difference and stored as the phase difference-velocitycharacteristic.

In step S2806, the width and the central value of the dead zone wherethe driving velocity does not exceed a predetermined value even if thephase difference changes, are calculated from the driving velocitycorresponding to each phase difference and stored.

This embodiment measures the phase difference-velocity characteristic,and calculates the width and central value of the dead zone and thechange rate of the driving velocity in the initial setting after theapparatus is started, but may execute them in a calibration operation inresponse to the instruction of the user. Alternatively, the measurementresult of the phase difference-velocity characteristic may be stored fora predetermined number of times, and the width and central value of thedead zone and the change rate of the driving velocity may be calculatedbased on the average value.

As described above, the configuration according to this embodimentincreases the change rate of the voltage amplitude as the absolute valueof the phase difference between the voltages applied to the vibrationwave motor decreases, and thus can suppress noise and maintain thecontrol performance in driving the vibration wave motor at a lowvelocity.

Countermeasure where Phase Difference at Center of Dead Zone Shifts from0°

Each of the dead zones illustrated in FIGS. 24A to 24C illustrates anexample in which the phase difference at the center of the dead zone is0°. The phase difference at the center of the dead zone is influenced bythe friction and the driving load of the driving unit, and thus ischanged according to operation environments. Thus, in a case where thephase difference at the center of the dead zone shifts from 0°, ameasure of increasing the change rate of the voltage amplitude as theabsolute value of the phase difference decreases, and a measure of usinga previously prepared measurement result of the phasedifference-velocity characteristic may not be so effective.

A description will now be given of a method of determining the changerate of the voltage amplitude from the target velocity of the panrotation unit 105 based on the voltage amplitude-velocity characteristicas a countermeasure in a case where the phase difference at the centerof the dead zone changes according to the operation environment.However, the basic flow is similar to a flow of the dead zonecountermeasure illustrated in FIG. 25 that increases the change rate ofthe voltage amplitude as the absolute value of the phase differencedecreases. The method of determining the voltage amplitude in step S2505is different.

FIG. 29 is a block diagram of the pan rotation unit 105 and the barrelrotation driving unit 112 in this embodiment. A difference between theconfiguration of FIG. 29 and the configuration of FIG. 26 is that thephase difference-velocity detecting unit 1130 is replaced with avoltage-velocity detecting unit 1132 and a target velocity setting unit1131 is added. Since other configurations are similar to those describedwith reference to FIG. 26 , a detailed description thereof will beomitted.

The target velocity setting unit 1131 sets a result of calculating thetarget velocity from a change amount (differential value) of the targetposition set by the target position setting unit 1123. Thevoltage-velocity detecting unit 1132 detects a relationship between thevoltage amplitude of the two-phase voltage determined by conversion unit1127 and the driving velocity detected by velocity detecting unit 1129.

The PID calculating unit 1124 performs the well-known PID calculationand calculates a control amount using as an input a deviation, which isa difference between the target position of the pan rotation unit 105set by the target position setting unit 1123 and an actual position ofthe pan rotation unit 105 detected by the position calculating unit1122. The conversion unit 1127 determines a phase difference between thetwo-phase voltages based on the control amount calculated by the PIDcalculating unit 1124, and determines the amplitude of the two-phasevoltages based on the target velocity set by the target velocity settingunit 1131 and the voltage-velocity characteristic detected by thevoltage-velocity detecting unit 1132. A procedure for detecting thevoltage-velocity characteristic by the voltage-velocity detecting unit1132 will be described.

FIG. 31 is a flowchart illustrating processing of measuring and storingthe voltage-velocity characteristic. The voltage-velocity characteristicis measured and stored in the initial settings of the tilt rotation unit104 and the pan rotation unit 105 in the step S601 described withreference to FIG. 6 .

In step S3101, the voltage (0V in this embodiment) for startingmeasurement of the voltage-velocity characteristic is set. Thisembodiment sets the phase difference to 90° as the upper limit value(which is a phase difference that maximizes the driving velocity).

In step S3102, the driving velocity for the voltage is detected based ona driving velocity at each voltage detected by the velocity detectingunit 1129.

In step S3103, it is detected whether or not the set voltage is thevoltage (Dmax in this embodiment) that ends the measurement of thevoltage-velocity characteristic. In a case where it is determined thatthe set voltage is the voltage that ends the measurement of thevoltage-velocity characteristic, the flow proceeds to step S3105;otherwise, the flow proceeds to step S3104 to change the voltage. Instep S3105, the driving velocity corresponding to each voltage measuredin step S3102 is stored as the voltage-velocity characteristic in theform illustrated in FIG. 30 .

In step S3106, the target velocity-voltage characteristic is calculatedfrom the voltage-velocity characteristic and stored. A method ofcalculating the target velocity-voltage characteristic will bedescribed.

Where k is an amplitude voltage in a case where the target velocity SPDis given, the target velocity-voltage characteristic is expressed by thefollowing expression (10):

$\begin{matrix}{k = {{D\min} + {\left( {{D\max} - {D\min}} \right){\sin\left( {\frac{SPD}{SPD\_ max}\frac{\pi}{2}} \right)}}}} & (10)\end{matrix}$where Dmin is a lower limit of the voltage amplitude (voltage amplitudein a case where the target velocity is 0), Dmax is an upper limit of thevoltage amplitude, and SPD_max is a velocity where the voltage amplitudeis Dmax and the phase difference is maximum (90° in this embodiment). Achange rate k′ of the voltage amplitude against the target velocity isexpressed by the following expression (11), and the smaller the targetvelocity SPD is, the higher the change rate of the voltage amplitudebecomes:

$\begin{matrix}{k^{\prime} = {\frac{\left( {{D\max} - {D\min}} \right)}{SPD\_ max}\frac{\pi}{2}{\cos\left( {\frac{SPD}{SPD\_ max}\frac{\pi}{2}} \right)}}} & (11)\end{matrix}$

This embodiment assumes that the operation of calculating and storingthe target velocity-voltage characteristic from the voltage-velocitycharacteristic is executed in the initial setting at the startup of theapparatus. Another method may be a method of measuring and storing thetarget velocity-voltage characteristic at the timing instructed by theuser. Alternatively, steps S3101 to S3104 may be repeated apredetermined number of times in one set, and SPD_max in expression (10)may be calculated and set based on a characteristic of an average valueof velocity detection results at each voltage.

Another method may be finding an approximate function of the targetvelocity-voltage characteristic using the least squares method. Adescription will now be given of a method of finding an approximationfunction of the target velocity-voltage characteristic using the leastsquares method. First, coefficients a, b, and c are found from thevoltage-velocity characteristic stored in step S3105 by setting theapproximate function of the target velocity-voltage characteristic tothe following expression (12):SPD=ak ² +bk+c  (12)

Next, a, b, and c are found where an error function L expressed byexpression (13) is minimum, based on the voltage-velocity characteristicstored in step S3105 and expression (14). Expression (14) is asimultaneous equation created under the condition that the partialdifferentiation results of L in expression (13) with respect to a, b,and c are zero. N in expressions (13) and (14) denotes the number ofdetections of the voltage-velocity characteristic in S3102, and N=4 inthis embodiment, as illustrated in FIG. 30 .

$\begin{matrix}{{L\left( {a,b,c} \right)} = {{\sum}_{i = 1}^{N}\left\{ {{SPD_{i}} - \left( {{ak_{i}^{2}} + {bk_{i}} + c} \right)} \right\}^{2}}} & (13)\end{matrix}$ $\begin{matrix}{\begin{pmatrix}a \\b \\c\end{pmatrix} = {\begin{pmatrix}{{\sum}_{i = 1}^{N}k_{i}^{4}} & {{\sum}_{i = 1}^{N}k_{i}^{3}} & {{\sum}_{i = 1}^{N}k_{i}^{2}} \\{{\sum}_{i = 1}^{N}k_{i}^{3}} & {{\sum}_{i = 1}^{N}k_{i}^{2}} & {{\sum}_{i = 1}^{N}k_{i}} \\{{\sum}_{i = 1}^{N}k_{i}^{2}} & {{\sum}_{i = 1}^{N}k_{i}} & {{\sum}_{i = 1}^{N}1}\end{pmatrix}^{- 1}\begin{pmatrix}{\sum}_{i = 1}^{N} & {k_{i}^{2}SPD_{i}} \\{\sum}_{i = 1}^{N} & {k_{i}SPD_{i}} \\{\sum}_{i = l}^{N} & {SPD_{i}}\end{pmatrix}}} & (14)\end{matrix}$

From expression (12), the voltage amplitude is expressed by expression(15). The conversion unit 1127 converts the target velocity SPD set bythe target velocity setting unit 1131 into the voltage amplitudecalculated by expression (15).

$\begin{matrix}{k = \frac{{- b} + \sqrt{b^{2} - {4{a\left( {c - {SPD}} \right)}}}}{2a}} & (15)\end{matrix}$

This embodiment has discussed a method that uses an approximateexpression and the second-order least squares method, but may use anapproximate expression of a polynomial equal to or higher than thesecond order. Any other approximate method, such as exponentialapproximation or exponential approximation, can be used as long as thechange rate of the voltage amplitude increases as the target velocitydecreases.

As described above, the configuration according to this embodimentincreases the change rate of the voltage amplitude as the target drivingvelocity of the vibration wave motor decreases, and can suppress thedeterioration of the control performance due to the influence of thedead zone even if the phase difference at the center of the dead zonechanges. As a result, this embodiment can suppress noise and secure thecontrol performance in driving the vibration wave motor at a lowvelocity regardless of the operation environment.

Other Embodiments

Embodiment(s) of the disclosure can also be realized by a computer of asystem or apparatus that reads out and executes computer-executableinstructions (e.g., one or more programs) recorded on a storage medium(which may also be referred to more fully as a ‘non-transitorycomputer-readable storage medium’) to perform the functions of one ormore of the above-described embodiment(s) and/or that includes one ormore circuits (e.g., application specific integrated circuit (ASIC)) forperforming the functions of one or more of the above-describedembodiment(s), and by a method performed by the computer of the systemor apparatus by, for example, reading out and executing thecomputer-executable instructions from the storage medium to perform thefunctions of one or more of the above-described embodiment(s) and/orcontrolling the one or more circuits to perform the functions of one ormore of the above-described embodiment(s). The computer may comprise oneor more processors (e.g., central processing unit (CPU), microprocessing unit (MPU)) and may include a network of separate computersor separate processors to read out and execute the computer-executableinstructions. The computer executable instructions may be provided tothe computer, for example, from a network or the storage medium. Thestorage medium may include, for example, one or more of a hard disk, arandom-access memory (RAM), a read-only memory (ROM), a storage ofdistributed computing systems, an optical disk (such as a compact disc(CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flashmemory device, a memory card, and the like.

The disclosure of this embodiment includes the following configurationsand methods.

(Configuration 1)

A driving control apparatus configured to control a driving unit thatmoves relative to each other a vibrator that is excited to vibrate byapplying a first driving signal and a second driving signal that have aphase difference with each other, and a contact member that contacts thevibrator, the driving control apparatus comprising at least oneprocessor, and a memory coupled to the at least one processor, thememory having instructions that, in a case where executed by theprocessor, perform operations as:

-   -   a first control unit configured to control the phase difference;        and    -   a second control unit configured to control a voltage amplitude        of each of the first driving signal and the second driving        signal,    -   wherein the second control unit controls the voltage amplitude        so that a change rate of the voltage amplitude increases as an        absolute value of the phase difference decreases.

(Configuration 2)

The image pickup apparatus according to Configuration 1, wherein thedriving unit is a vibration wave motor that vibrates based on a signalapplied to each of two electrodes.

(Configuration 3)

The driving control apparatus according to configuration 1 or 2, whereinthe change rate of the voltage amplitude is determined based on a sinewave function.

(Configuration 4)

The driving control apparatus according to any one of Configurations 1to 3, wherein the instructions further performs operations as:

-   -   a first detecting unit configured to detect a driving velocity        of the driving unit; and    -   a second detecting unit configured to detect a relationship        between the phase difference and the driving velocity.

(Configuration 5)

The driving control apparatus according to Configuration 4, wherein thesecond detecting unit detects a width of the phase difference and acentral phase difference of a dead zone in which a change amount of thedriving velocity relative to a change amount of the phase difference issmaller than a predetermined value, and

-   -   wherein the change rate of the voltage amplitude is controlled        so that the closer the phase difference is to the central phase        difference, the larger the phase difference becomes.

(Configuration 6)

The driving control apparatus according to Configuration 4 or 5, whereinthe change rate of the voltage amplitude is controlled based on areciprocal of the phase difference and a change rate of the drivingvelocity.

(Configuration 7)

An image pickup apparatus comprising:

-   -   the driving control apparatus according to any one of        Configurations 1 to 6; and    -   an imaging unit configured to capture an object and generates an        image.

(Method 1)

A control method configured to control a driving unit that movesrelative to each other a vibrator that is excited to vibrate by applyinga first driving signal and a second driving signal that have a phasedifference with each other, and a contact member that contacts thevibrator, the control method comprising:

-   -   a first control step configured to control the phase difference;        and    -   a second control step configured to control a voltage amplitude        of each of the first driving signal and the second driving        signal,    -   wherein the second control step controls the voltage amplitude        so that a change rate of the voltage amplitude increases as an        absolute value of the phase difference decreases.

(Configuration 8)

A driving control apparatus that controls a driving unit that moves avibrator that is excited to vibrate by applying a first driving signaland a second driving signal that have a phase difference with eachother, and a contact member that contacts the vibrator relative to eachother, the driving control apparatus comprising at least one processor,and a memory coupled to the at least one processor, the memory havinginstructions that, in a case where executed by the processor, performsoperations as:

-   -   a first control unit that controls the phase difference; and    -   a second control unit for controlling the voltage amplitudes of        the first driving signal and the second driving signal,    -   wherein the second control unit controls the voltage amplitude        such that the change rate of the voltage amplitude increases as        the target velocity of the driving unit decreases.

(Configuration 9)

The driving control apparatus according to configuration 8, wherein thedriving unit is a vibration wave motor that vibrates based on a signalapplied to each of two electrodes.

(Configuration 10)

The driving control apparatus according to configuration 8 or 9, whereinthe change rate of the voltage amplitude is determined based on a sinewave function.

(Configuration 11)

The driving control apparatus according to any one of Configurations 8to 10, wherein the instructions further performs operations as:

-   -   a first detecting unit configured to detect a driving velocity        of the driving unit; and    -   a second detecting unit configured to detect a relationship        between the phase difference and the driving velocity.

(Configuration 12)

The driving control apparatus according to Configuration 11, wherein thechange rate of the voltage amplitude is controlled based on the changerate of the voltage amplitude and the driving velocity.

(Composition 13)

An image pickup apparatus comprising:

-   -   the driving control apparatus according to any one of        Configurations 8 to 12; and    -   an imaging unit configured to capture an object and generates an        image.

(Method 2)

A control method configured to control a driving unit that movesrelative to each other a vibrator that is excited to vibrate by applyinga first driving signal and a second driving signal that have a phasedifference with each other, and a contact member that contacts thevibrator, the control method comprising:

-   -   a first control step configured to control the phase difference;        and    -   a second control step configured to control a voltage amplitude        of each of the first driving signal and the second driving        signal,    -   wherein the second control step controls the voltage amplitude        so that a change rate of the voltage amplitude increases as a        target velocity of the driving unit decreases.

While the disclosure has been described with reference to exemplaryembodiments, it is to be understood that the disclosure is not limitedto the disclosed exemplary embodiments. The scope of the followingclaims is to be accorded the broadest interpretation so as to encompassall such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2021-199261, filed on Dec. 8, 2021, and No. 2022-145279, filed on Sep.13, 2022, each of which is hereby incorporated by reference herein inits entirety.

What is claimed is:
 1. A driving control apparatus configured to control a driving unit that moves relative to each other a vibrator that is excited to vibrate by applying a first driving signal and a second driving signal that have a phase difference with each other, and a contact member that contacts the vibrator, the driving control apparatus comprising at least one processor, and a memory coupled to the at least one processor, the memory having instructions that, in a case where executed by the processor, perform operations as: a first control unit configured to control the phase difference; and a second control unit configured to control a voltage amplitude of each of the first driving signal and the second driving signal, wherein the second control unit controls the voltage amplitude so that a change rate of the voltage amplitude increases as an absolute value of the phase difference decreases.
 2. The driving control apparatus according to claim 1, wherein the driving unit is a vibration wave motor that vibrates based on a signal applied to each of two electrodes.
 3. The driving control apparatus according to claim 1, wherein the change rate of the voltage amplitude is determined based on a sine wave function.
 4. The driving control apparatus according to claim 1, wherein the instructions further performs operations as: a first detecting unit configured to detect a driving velocity of the driving unit; and a second detecting unit configured to detect a relationship between the phase difference and the driving velocity.
 5. The driving control apparatus according to claim 4, wherein the second detecting unit detects a width of the phase difference and a central phase difference of a dead zone in which a change amount of the driving velocity relative to a change amount of the phase difference is smaller than a predetermined value, and wherein the change rate of the voltage amplitude is controlled so that the closer the phase difference is to the central phase difference, the larger the phase difference becomes.
 6. The driving control apparatus according to claim 4, wherein the change rate of the voltage amplitude is controlled based on a reciprocal of the phase difference and a change rate of the driving velocity.
 7. An image pickup apparatus comprising: the driving control apparatus according to claim 1; and an imaging unit configured to capture an object and generates an image.
 8. A control method configured to control a driving unit that moves relative to each other a vibrator that is excited to vibrate by applying a first driving signal and a second driving signal that have a phase difference with each other, and a contact member that contacts the vibrator, the control method comprising: a first control step configured to control the phase difference; and a second control step configured to control a voltage amplitude of each of the first driving signal and the second driving signal, wherein the second control step controls the voltage amplitude so that a change rate of the voltage amplitude increases as an absolute value of the phase difference or a target velocity of the driving unit decreases.
 9. A driving control apparatus configured to control a driving unit that moves relative to each other a vibrator that is excited to vibrate by applying a first driving signal and a second driving signal that have a phase difference with each other, and a contact member that contacts the vibrator, the driving control apparatus comprising at least one processor, and a memory coupled to the at least one processor, the memory having instructions that, in a case where executed by the processor, perform operations as: a first control unit configured to control the phase difference; and a second control unit configured to control a voltage amplitude of each of the first driving signal and the second driving signal, wherein the second control unit controls the voltage amplitude so that a change rate of the voltage amplitude increases as a target velocity of the driving unit decreases.
 10. The driving control apparatus according to claim 9, wherein the driving unit is a vibration wave motor that vibrates based on a signal applied to each of two electrodes.
 11. The driving control apparatus according to claim 9, wherein the change rate of the voltage amplitude is determined based on a sine wave function.
 12. The driving control apparatus according to claim 9, wherein the instructions further performs operations as: a first detecting unit configured to detect a driving velocity of the driving unit; and a second detecting unit configured to detect a relationship between the phase difference and the driving velocity.
 13. The driving control apparatus according to claim 12, wherein the change rate of the voltage amplitude is controlled based on the voltage amplitude and a change rate of the driving velocity.
 14. An image pickup apparatus comprising: the driving control apparatus according to claim 9; and an imaging unit configured to capture an object and generates an image. 